Rechargeable battery packs may provide a power source for cordless power tools. The battery pack may have a battery with a design voltage and may provide power to operate a power tool. The battery itself may consist of a number of individual battery cells that may be combined within the battery pack to provide a desired voltage. A lithium-ion battery may have a design voltage such as 18, 15, 12, or 9 volts, by way of non-limiting example. It may be desired to prevent overcharging of any battery cell within a lithium-ion battery, such as by disabling charging of the battery cells.
The batteries may include an internal discharge switch, such as an FET, that the battery uses to disable/enable use (discharge) of the battery. The inclusion of this discharge switch in the battery is an additional expense and takes up space within the battery pack. It may be desired to remove the discharge switch from the battery pack.
Lithium-ion batteries may be subject to a soft short circuit if the voltage of the battery pack is held at a low value. A soft short circuit may develop into a hard short circuit which may ruin the battery pack. It may be desired to prevent operation of the battery pack at a low voltage and to prevent or minimize the possibility for creating soft short circuits. Further, it may be desired to monitor the charging of the battery and conduct a pre-charge operation to ascertain the condition of the battery pack prior to implementing a fast or rapid charge operation.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.